PACIFIC PALISADES, California (Reuters) - Former champion Bubba Watson birdied three of the last eight holes, and conjured a brilliant up-and-down on 18, to edge one stroke clear of a congested leaderboard in the Northern Trust Open third round on Saturday.

The American left-hander used his booming length off the tee and his creativity around the greens to good advantage as he fired a four-under-par 67 at a sun-splashed Riviera Country Club, a venue he has always relished playing.

Champion here in 2014, Watson mixed five birdies with a lone bogey on a firm and fast-running layout to post a 12-under total of 201, one better than fellow Americans Dustin Johnson (68), Chez Reavie (69) and Jason Kokrak (70), the overnight leader.

Rory McIlroy (67) was a further stroke back at 10-under, level with Australians Adam Scott (67) and Marc Leishman (68), South Korean KJ Choi (67) and American Kevin Chappell (66), to set up the prospect of a thrilling shootout in Sunday's final round.

"We all feel good about our chances, even the guy that's five (shots) back," twice Masters champion Watson told reporters after covering his back nine in three-under 33.

"I'm going to go out and try to do the same thing, keep my head down ... slow it down and hopefully it works out with one or two pars and one or two birdies giving me the victory."

Watson seized the outright lead with birdies at the 11th, 13th and 17th and maintained it with a clutch up-and-down at the par-four last.

After missing the fairway off the tee, his second shot ended up under an electronic scoreboard below the green to the right from where he hit a superb lob wedge to within three feet of the pin.

"The up-and-down was nice," grinned Watson. "You have the ability to do it, but at that moment, can you do it?

"I'm very happy. The last few days have been good. It's all about the steadiness on the greens. Working really hard to make sure I don't lose anything from three foot and in because you can easily do it here."

Long-hitting Johnson, a runner-up at Riviera for the last two years, was one of five players who held at least a share of the lead during the third round before winding up with a five-birdie 68.

"I'm definitely happy with my position," said the nine-times PGA Tour winner. "The last three rounds I've played pretty solid. A few mistakes here and there but it's going to happen.

"Somebody's going to shoot low tomorrow. There's so many great players within a couple shots of the lead. I would guess 17-under, 16-under, would get it done."

Reavie briefly stormed two shots clear with an eagle at the driveable par-four 10th where his tee shot ended up just off the front left edge of the green from where he sank a curling 33-foot putt.

However, he then slid back with consecutive bogeys at the 14th and 15th.